1. Technical Field
The present invention relates to method and arrangement for providing a gas turbine that includes a duct for carrying gas from a gas turbine inlet to a gas turbine outlet and an outer housing arranged radially outside a wall structure which defines the radially outer limits of the gas duct. The gas turbine, between the inlet and outlet, is constructed from a plurality of modules, each of which includes a part of the outer housing and a part of the wall structure of the gas duct. At least two adjacent parts of the wall structure of the gas duct are arranged at a distance from one another. At least one pressure dividing element provided that is configured to divide off a pressure area in the gas duct at the junction between the two adjacent parts of the wall structure from another pressure area situated between the wall structure of the gas duct and the outer housing.
2. Background
Gas turbines of the aforementioned type are used, for example, as engines for vehicles and aircraft, as prime movers in ships, and in power stations for the generation of electricity.
Manufacturing the gas turbine in modules, which are then assembled into a complete gas turbine, is already known in the case of gas turbines having a compressor driven by a turbine and a combustion chamber arranged between them, together with a power turbine arranged down-stream of the turbine. In this case, each of the modules carries various main components of the gas turbine, such as compressor, combustion chamber, turbine and power turbine. A gas duct which carries gas from one main component to another furthermore extends through the modules.
Manufacturing the gas turbine in modules facilitates both assembly and servicing of the gas turbine.
One problem in connection with assembly of the modules is obtaining satisfactory tightness at the transition of the gas duct between two adjacent modules. At the gas duct transition from a first module to a second module, sealing elements of the metal sealing ring type are generally used. The sealing rings are in this case arranged in radial grooves in the gas duct wall structure of the first module and protrude somewhat outside the outer circumferential surface of the wall structure. In the end section facing the gas duct of the first module, the gas duct wall structure of the second module is designed with an inside diameter somewhat larger than the diameter of the outer circumferential surface of the first gas duct. This makes it possible to introduce the gas duct of the first module into the gas duct of the second module, the sealing rings finishing up in a clamped position between the outer and inner surfaces respectively of the two ducts.
One problem with the aforementioned type of sealing element, however, is that they are never completely tight and that they are greatly affected by circularity defects in the seal positioning, a condition which often occurs in gas turbine engines due to the high temperatures and temperature differentials which occur in these engines. Another problem in connection with this type of seals is that they only assume their final sealing position when the modules are fully assembled, which means that it is not possible to visually verify that the seals have assumed a correct position.